Version 2!

Added speaker grilles, battery level indicator, 2x battery life, and removable handle/legs.

Portable Bluetooth Speaker!

It is very bass heavy, and plenty loud for indoor and outdoor listening. It uses a single 4 inch Dayton Audio midrange driver and a 4 inch passive radiator.

Split into halves to allow for easy assembly and to be printable on a 120mm square build surface.

It uses 6 18650 cells. I used 3000mah Samsung cells in 3s2p and it lasts hours. It can play music while charging.

Build List:

The amplifier is an aideepen TDA7492P from Amazon. Any bluetooth amplifier between 40 and 50 watts with 12v input will work.
https://www.amazon.com/Aideepen-TDA7492P-Amplifier-Wireless-Bluetooth/dp/B01N3UM7TM

The speaker is a dayton audio treated paper cone 4 inch midbass woofer 8 ohm version on parts express.com.

The passive radiator is a 4 inch from Dayton's ND series, also on parts express.com. I have added a block off plate and a tuned bass port for those who prefer a sealed or vented enclosure. The length of the bass port tip can be scaled in your slicer to fine tune the port length.

The passive radiator has more excursion than the woofer, which is why I'm able to get away with same diameter radiator as woofer. It's not perfect, but High notes exit the front, and bass comes out the back. This works because bass travels in all directions.

This is the 3s battery balance board I used, although any 3s BMS that both charges and balances with low voltage cutoff will work:
https://www.amazon.com/dp/B075D96HVV/ref=cm_sw_r_cp_apa_i_7fKOFb22F8H17?_encoding=UTF8&psc=1

This is the power button I used, although any latching 16mm button will work:
https://www.amazon.com/dp/B07RFPKSKY?ref=ppx_pop_mob_ap_share

The charge port is a 2.1x5.5 barrel connector that came in a 12 pack on amazon.

I used the 12.6v 2A power supply with a 2.1x5.5 barrel connector as a suitable charger for the speaker. It came with the amplifier.

The screws I used are just some I had laying around, but the screw holes are 0.1 inch diameter.

The nubs on the halves are 0.24in and the nub holes are 0.25in, so they click together. I'd also recommend using liquid nails or adhesive to further join the halves.